Power transmission apparatus for an automobile

ABSTRACT

Disclosed is a power transmission apparatus for an automobile comprising an engine  1 , a generator  15  driven by an output of the engine  1 , and a motor  29  driven by a generation output of the generator  15  and a discharge output of a battery  47 , wherein a clutch mechanism  23  is provided between an output shaft of the engine  1  and an output shaft of the generator  15 . In a hybrid vehicle, a loss caused by an inertia torque of the generator can be avoided.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a construction of a power trainsystem comprising an internal combustion engine (hereinafter referred toas an engine), an electric power device (hereinafter referred to as amotor) and a power transmission apparatus, and particularly to a powertransmission apparatus adapted to enhance the transmission efficiency ofthe power train system.

[0002] Japanese Patent Laid-Open No. Hei 8-98322 discloses a knownexample using a power transmission apparatus adapted to enhance thetransmission efficiency of the power train system.

[0003] In the above publication, there is described a power trainconstruction in which an engine and a generator are connected to eachother through a speed increasing gear, and a torque from an output shaftof the generator is transmitted to a motor through a clutch. In theabove-described power train construction, since the generator and themotor permit high accuracy adjustment of the number of revolutions ofthe output shaft, torque variation at the time of switching between aseries mode and a parallel mode (series mode: running by only the motorusing energy generated by the engine; parallel mode: running by theengine and the motor) caused by engagement and disengagement of theclutch can be suppressed.

[0004] It is necessary for the above-described system to syntheticallycontrol the engine, the motor and the generator so that an operator (adriver) may operate the engine and the motor in a high efficiency regionwhile satisfying acceleration and deceleration required by an operator.Therefore, a constitution is provided in which the engine is connectedto the generator, and a torque from the output shaft of the generator istransmitted to the motor through the clutch.

[0005] With this constitution, in the case where the vehicle is intendedto be accelerated in the state in which the clutch is engaged (theparallel mode), an inertia torque of a generator rotating portionoccurs, and it is necessary to correct a torque corresponding to theinertia torque by the engine or the motor. Thus, it is impossible toavoid an increase in fuel consumption due to the inertia torque.

SUMMARY OF THE INVENTION

[0006] In view of the foregoing, it is an object of the presentinvention, in the case where the aforementioned parallel mode operationis employed and charging of a battery is not necessary, to suppress thegeneration of the inertia torque thereby improving fuel economy of thevehicle.

[0007] For achieving the aforementioned object, there is provided apower transmission apparatus for an automobile comprising an engine, agenerator driven by an output of the engine, a battery charged by ageneration output of the generator, and a motor driven by a dischargeoutput of the battery, wherein a clutch mechanism is provided between anoutput shaft of the engine and an output shaft of the generator.

[0008] Preferably, the clutch mechanism is a device which requires noenergy for engagement and disengagement when it is engaged ordisengaged.

[0009] Preferably, the clutch of the clutch mechanism is a dog clutch.

[0010] Preferably, there is used a clutch mechanism using a linearactuator (e.g. a motor, a gear and a rack) for driving the dog clutch.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 shows a constitutional view of a hybrid automobile systemaccording to one embodiment of the present invention;

[0012]FIG. 2 shows a control block diagram of FIG. 1;

[0013]FIG. 3 shows the target torque characteristics of a drive shaft ofFIG. 1;

[0014]FIG. 4 shows shift command characteristics of FIG. 1;

[0015]FIG. 5 shows a system constitutional view in a series mode of FIG.1;

[0016]FIG. 6 shows a system constitutional view in a parallel mode atlow speed of FIG. 1;

[0017]FIG. 7 shows a system constitutional view in a parallel mode athigh speed of FIG. 1;

[0018]FIG. 8 shows a time chart at the time of operation in a seriesmode of FIG. 1;

[0019]FIG. 9 shows a time chart at the time of operation in a parallelmode of FIG. 1;

[0020]FIG. 10 shows a time chart at the time of switching a shiftmechanism of FIG. 1;

[0021]FIG. 11 shows a time chart at the time of trouble of an actuatorof FIG. 1; and

[0022]FIG. 12 shows one example of a wobble motor applied to a linearactuator of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The embodiments according to the present invention will bedescribed in detail hereinafter with reference to the drawings.

[0024]FIG. 1 shows a construction of a hybrid automobile systemaccording to one embodiment of the present invention. In the systemshown in FIG. 1, an output shaft 2 of an engine 1 has a gear 4 on theengine side for low speed having a meshing gear 3, a gear 6 on theengine side for high speed having a meshing gear 5, a hub 7 and a sleeve8 for directly connecting the gear 4 on the engine side for low speed orthe gear 6 on the engine side for high speed with the output shaft 2. Astopper (not shown) is provided so that the gear 4 on the engine sidefor low speed and the gear 6 on the engine side for high speed may notmove in an axial direction of the output shaft 2. The hub 7 isinternally provided with grooves (not shown) engaged with a plurality ofgrooves 9 of the output shaft 2. The hub 7 is movable in an axialdirection of the output shaft 2, but the movement of the hub 7 in arotational direction of the output shaft 2 is limited. Thereby, thetorque output from the engine 1 is transmitted to the hub and thesleeve. In order to transmit the torque from the engine 1 to the gear 4on the engine side for low speed or the gear 6 on the engine side forhigh speed, it is necessary to move the sleeve 8 in an axial directionof the output shaft 2 to directly connect the meshing gear 3 or 5 to thehub 7. The meshing gears 3 and 5 and the hub 7 are provided with thesame grooves, and the sleeve 8 is internally provided with a groove (notshown) engaged with the sleeve 7. For movement of the sleeve 8, there isprovided a linear actuator comprising a rack 11, a pinion 12 engagedwith the rack 11, and a stepping motor (1) 13. The outer peripheralportion of the sleeve 8 is made free in the rotational direction of theoutput shaft 2, and a lever 14 is provided which is not rotated withrespect to the rotation of the sleeve 8. The clutch mechanism comprisingthe hub 7, the sleeve 8, the meshing gear 3 and the meshing gear 5 iscalled a dog clutch. This mechanism enables the transmission of energyfrom a power source such as the engine 1 to a tire 10 with highefficiency to improve fuel economy. Since the stepping motor (1) 13 canrecognize the rotational angle by the number of steps preset, a movingposition of the rack 11 can be judged. It is therefore possible to judgewhether or not the gear 4 on the engine side for low speed or the gear 6on the engine side for high speed is used at present, or the position isin a neutral position. The above-described judgement can be made by acombination of a sensor for detecting a position of the rack and a DCmotor in place of the stepping motor.

[0025] The above-described clutch mechanism and the linear actuator arealso applied to the direct connection between the output shaft 2 of theengine 1 and an output shaft 16 of a generator 15. The output shaft 2 isprovided with a gear 18 for detecting the engine speed Ne of the engine1 having a meshing gear 17 rotated integrally with the output shaft 2.Further, the output shaft 16 is provided with a gear 22 for detectingthe speed Ng of the generator 15 having a meshing gear 21 and a hub 20movable along a groove 19 in the axial direction of the output shaft 16.A sleeve 23 is provided in the outer periphery of the hub 20. Further, athrust bearing 24 is provided between the output shaft 2 and the outputshaft 16 to reduce the frictional resistance caused by the contactbetween the two output shafts and prevent a deviation of the shaft. Thelinear actuator portion is composed of a lever 25, a rack 26, a pinion27 and a stepping motor (2) 28.

[0026] An output shaft 30 of a motor 29 for driving a vehicle (notshown) is provided with a gear 31 on the motor side for low speed meshedwith the gear 4 on the engine side for low speed and a gear 32 on themotor side for high speed meshed with the gear 6 on the engine side forhigh speed. The gear 31 on the motor side for low speed is also used fordetecting the speed Nm of the motor 29. Further, the output shaft 30 isprovided with a final differential gear 33 to enable the running of thevehicle by only the motor 29.

[0027] In the engine 1, the intake airflow rate is controlled by anelectronically controlled throttle 35 (comprising a throttle valve 36, adriving motor 37 and a throttle sensor 38) provided on an intakemanifold 34 so that the fuel flow rate corresponding to the intakeairflow rate is ejected from fuel injectors 39. The igniting timing isdetermined from signals of the air/fuel ratio, the engine speed and soon determined from the airflow rate and the fuel flow rate, and ignitionis made by an ignitor 40. The fuel injectors 39 include an intake portinjection system in which fuel is injected to an intake port, or adirect injection system in which fuel is injected directly into acylinder. Preferably, operating regions required by the engine (regionsdetermined by the engine torque and the engine speed) are compared toselect an engine of the system which can improve fuel economy and hasthe excellent exhaust performance.

[0028] Next, the control device for the engine 1, the generator 15 andthe motor 29 will be explained with reference to FIG. 2, a control blockdiagram, FIG. 3, a target drive shaft torque characteristic, and FIG. 4,a shift command characteristic. First, into a power train control unit41 of FIG. 1 are input an accelerator pedal angle a, a brake pedal forceβ, a shift lever position Ii, a battery capacity Vb, the speed Nm of themotor 29 detected by a motor speed detector 42, the engine speed Nedetected by an engine speed detector 43, and the generator speed Ngdetected by a generator speed detector 44. In the power train unit 41,torque of the engine 1 is calculated, and transmitted to an enginecontrol unit 45 by LAN as communication means. Within the engine controlunit 45, an opening degree of a throttle valve for achieving the enginetorque, the fuel flow rate and the ignition timing are calculated, andtheir respective actuators are controlled. Further, in the power traincontrol unit 41, the torques of the motor 29 and the generator 15, andthe number of steps of the stepping motor (1) 13 and the stepping motor(2) 28 are calculated, and transmitted to the motor control unit 46 byLAN so that the actuators therefor are controlled. The motor controlunit 46 allows to charge electric power obtained from the generator 15in a battery 47 and supply power from the battery 47 to drive the motor29 and the like. Referring to FIG. 2, in the power train control unit41, first, the vehicle speed Vsp is calculated by the function f fromthe motor speed Nm in the process 48. Then, in the process 49, thetarget drive shaft torque Ttar intended by an operator is calculatedfrom the vehicle speed Vsp, the accelerator pedal angle a, the brakepedal force β, and the shift lever position Ii. In the process 50, ashift command Ss is calculated from the target drive shaft torque Ttarand the vehicle speed Vsp to select the gear 3 for low speed or the gear6 for high speed. Finally, in the process 51, torques of the actuators(an engine torque Te, a motor torque Tm and a generator torque Tg), astep number Sn1 of the stepping motor (1), and a step number Sn2 of thestepping motor (2) are calculated from the target drive shaft torqueTtar, the vehicle speed Vsp, the battery capacity Vb, the engine speedNe and the generator speed Ng, and output.

[0029] In FIG. 3, the axis of abscissa indicates the vehicle speed Vsp,and the axis of ordinate indicates the target drive shaft torque Ttar. Aportion above a point of intersection of the two axes represents thatthe drive torque is positive, while a portion below represents that thedrive torque is negative. A portion on the right hand of the point ofintersection represents a forward travel, while a portion on the lefthand represents a backward travel. The solid line indicates theaccelerator pedal angle α (%), and the diagonal line indicates the brakepedal force β. The larger % of the accelerator pedal angle a, the largerthe target drive shaft torque Ttar because an operator demands a greatacceleration feeling. In case of the backward travel, since the vehiclespeed need not be increased, the target drive shaft torque is small. Thebrake pedal force β shows a high value in the lower part in FIG. 3, itindicates that an operator demands a great deceleration. In the lowvehicle speed at which the accelerator pedal angle α is 0%, the targetdrive torque is positive to generate the torque of the motor 29 so as tosimulate the generation of the maximum torque at stall speed using atorque converter.

[0030] Next, the applied operating regions of the engine 1 and the motor29 will be explained. The mesh region is a motor driving region, and thediagonal region is an engine driving region. Normally, in a region wherethe target drive shaft torque Ttar is small at the time of the forwardtravel and the backward travel in terms of the compact and light weightof the engine 1 and the motor 2 and the improvement in fuel economyresulting from the high efficiency operation, it is necessary to driveonly the motor 1. Further, in the case where the target drive shafttorque Ttar is negative, the revival operation of the motor 1 isexecuted to make the deceleration demanded by an operator and theimprovement in fuel economy by recovery of energy compatible.

[0031]FIG. 4 shows the shift command Ss characteristics of a shiftmechanism using the dog clutch for making the operation region of theengine 1 and the motor 29 highly efficient. In FIG. 4, the shift commandSs is determined by the vehicle speed Vsp and the target drive shafttorque Ttar. In the shift command Ss, the value in which the engine 1and the motor 29 has the maximum efficiency in the overall operationregion is obtained in advance by the experiment or simulation and storedin memory means (not shown) within the power train control unit 41.

[0032] The operation principle of the system constitution shown in FIG.1 will be explained with reference to FIGS. 5 to 10. FIG. 5 shows thesystem constitution in a series mode, FIG. 6 shows the systemconstitution in a parallel mode at the time of low speed, FIG. 7 showsthe system constitution in a parallel mode at the time of high speed,FIG. 8 is a time chart at the time of operation in a series mode, FIG. 9is a time chart at the time of operation in a parallel mode, and FIG. 10is a time chart at the time of switching a shift mechanism.

[0033] In FIG. 5, the series mode termed herein is an operation in whichthe generator 15 is driven by the engine 1, and the motor 29 is drivenby power charged in the battery 47 to run the vehicle. In this case, thestepping motor (1) 13 is rotated rightward, the rack 11 is movedleftward, and the sleeve 8 is set to a neutral position. Further, thestepping motor (2) 28 is rotated leftward, the rack 26 is movedrightward, and the sleeve 23 is set to the meshing gear 21 mounted onthe output shaft 16 of the generator 15. Thereby, the engine 1 drivesonly the generator 15 to enable charging the battery 47. Further, thegenerator 15 can be operated also as a motor, and the engine 1 isstarted by the generator 15. Next, one example of the running of thesystem shown in FIG. 5 will be explained with reference to FIG. 8. InFIG. 8, the axis of abscissa indicates the time, and the axis ofordinate indicates the shift lever position Ii, the accelerator pedalangle α, the brake pedal force β, the motor torque Tm, the vehicle speedVsp, the battery capacity Vb, the engine speed Ne, step number Sn1 ofthe stepping motor (1), step number Sn2 of the stepping motor (2), andthe generator speed Ng. The running conditions are the case where thevehicle starts from its stop state, and the accelerator pedal angle α ischanged during running. An operator applies a brake in the state wherethe shift lever position is N (neutral), and therefore, the vehiclestops. The battery capacity is also in a state requiring no charge. Whenthe battery capacity exceeds 75%, the efficiency lowers, and when it isnot more than 50%, the voltage drop is great to lower discharge power.It is therefore desirable that charging of the battery 47 is executed inthe mesh portion shown in FIG. 8. After the shift lever position hasbeen moved (a) to D (drive: forward) from N (neutral), the motor torqueTm is determined according to the accelerator pedal angle α. Immediatelyafter N to D shift (a), since the accelerator pedal angle α is 0% andthe vehicle is in a low speed, the motor torque Tm is positive by themaximum torque at stall rotation, so that the vehicle starts to run.Thereafter, the battery capacity Vb is reduced by the use of the motor29. At the time (b) when the battery capacity Vb is lower than 50%, thegenerator 15 is used as a motor to start the engine 1. Thereafter, thegenerator 15 is used as a generator and charging is executed by thetorque of the engine 1. In the case where an operator sets theaccelerator pedal angle α to 0% (c) and applies a brake (d), the revivalis executed by the motor 29 to charge the battery.

[0034] In FIG. 6, the parallel mode termed is an operation in which thegenerator 15 is driven by the engine 1, the motor 29 is driven by powercharged in the battery 47 to run the vehicle and at the same time thetorque of the engine 1 is applied to drive the vehicle. In this case,the stepping motor (1) 13 is rotated rightward, the rack 11 is movedleftward, and the sleeve 8 is set to the meshing gear 3 provided on thegear 4 on the engine side for low speed. Further, the stepping motor (2)28 is rotated rightward, the rack 26 is moved leftward, and the sleeve23 is set to the meshing gear 17 provided on the output shaft 2 of theengine 1. Thereby, the torque of the engine 1 is transmitted to the tire10 through the gear 4 on the engine side for low speed and the gear 31on the motor side for low speed. One example of the running of thesystem shown in FIG. 6 will be explained hereinafter with reference toFIG. 9. In FIG. 9, the axis of abscissa indicates the time, and the axisof ordinate indicates the shift lever position Ii, the accelerator pedalangle α, the brake pedal force β, the motor torque Tm, the engine torqueTe, the drive shaft torque To, the vehicle speed Vsp, the engine speedNe, step number Sn1 of the stepping motor (1), step number Sn2 of thestepping motor (2), and the generator speed Ng. The running conditionsare the case where the accelerator pedal angle α is changed duringrunning at constant vehicle speed. When the accelerator pedal angle α isgreatly applied (e), the target drive shaft torque Ttar increases.Therefore, it is necessary to increase the motor torque Tm and outputthe engine torque Te. Since at that time, the engine 1 and the generator15 are integrated, the output shaft 2 of the engine 1 is adjusted to thespeed (speed of the motor 29) of the gear 4 on the engine side for lowspeed by the generator 15, the stepping motor (2) is rotated to thepositive side (right rotation: movement leftward of the rack 11) at f,and the sleeve 8 is meshed with the meshing gear 3 of the gear 4 on theengine side for low speed. Thereby, the parallel mode is enabled byaddition of the smooth engine torque Te. When the accelerator pedalangle α lowers (g), only the engine torque Te is set to zero, andrunning is effected by only the motor torque Tm. At this time, the shiftcaused by the movement of the sleeve 8 is not carried out in terms ofreduction in shock at the time of deceleration.

[0035]FIG. 7 shows a parallel mode at the time of high speed. Here, thestepping motor (1) 13 is rotated leftward, the rack 11 is movedrightward, and the sleeve 8 is set to the meshing gear 5 provided on thegear 6 on the engine side for high speed. The stepping motor (2) 28 isrotated leftward, the rack 26 is moved rightward, and the sleeve 23 isdisengaged from the output shaft 2 of the engine 1. Thereby, the torqueof the engine 1 is transmitted to the tire 10 through the gear 6 on theengine side for high speed and the gear 32 on the motor side for highspeed. At acceleration, the generator 15 is disengaged from the outputshaft 2 and a torque corresponding to an inertia torque of the generatorcan be reduced. Therefore, it is not necessary to increase the torque ofthe engine 1 to improve fuel economy at acceleration. One example of therunning of the system shown in FIG. 7 will be explained hereinafter withreference to FIG. 10. In FIG. 10, the axis of abscissa indicates thetime, and the axis of ordinate indicates the shift command Ss, theaccelerator pedal angle α, the brake pedal force β, the motor torque Tm,the engine torque Te, the generator torque Tg, the drive shaft torqueTo, the vehicle speed Vsp, the engine speed Ne, step number Sn1 of thestepping motor (1), and step number Sn2 of the stepping motor (2). Therunning conditions are the case where the shift command Ss is changedduring running at constant accelerator pedal angle α. After the shiftcommand Ss has been changed (h), the shift is made by movement of thesleeve 8. Therefore, the engine torque Te and the generator torque Tgare increased temporaly, the step number Sn1 of the stepping motor (1)is set to negative, and the shift of the gear 6 on the engine side forhigh speed is executed. This is because of the fact that when torqueoccurs at the sleeve 8, the movement of the sleeve 8 is difficult. Sinceat the time of shift, the torque from the engine 1 lowers, the torque Tmof the motor 29 is increased disregarding the fuel cost to prevent thetorque from being lowered. The frequency of increase in the motor torqueTm is merely during the shift, not leading to an increase in fuel cost.

[0036]FIG. 11 is a time chart when an actuator is in trouble. In FIG.11, the axis of abscissa indicates the time, and the axis of ordinateindicates a fail-safe flag Ff, the shift command Ss, the acceleratorpedal angle α, the brake pedal force β, the motor torque Tm, the enginetorque Te, the generator torque Tg, the drive shaft torque To, thevehicle speed Vsp, step number Sn1 of the stepping motor (1), and stepnumber Sn2 of the stepping motor (2). The fail conditions are the casewhere the stepping motor (1) is not actuated, and the gear 4 on theengine side for low speed is fixed. In the case where the fail is judgedby the power train control unit 41 (j), running by the motor 29 and thegenerator 15 should be executed to avoid a danger, and an input from theengine 1 is cutoff. Thereby, the engine torque Te is smoothly set tozero from j to k to reduce the shock, and the step number Sn2 of thestepping motor (2) is returned to zero, and the generator 15 is set tobe used as a motor. In the case where as the fail condition, thestepping motor (2) is fixed to the output shaft 16 of the generator 15as shown by the diagonal line, the engine torque Te is likewise smoothlyset from j to k to reduce the shock, and the step number Sn2 of thestepping motor (1) is returned to zero to set the shift position to aneutral point. Thereby, running only by the motor 29 results, and it ispossible to suppress the shock to impart an operator unpleasant feelingand avoid a danger.

[0037]FIG. 12 shows an example in which a wobble motor is applied to alinear actuator. In the case of the system as described above, since thefrequency of shift is small, when energy of the dog clutch in theoperation other than the shift is not present, the power consumption canbe reduced, and the fuel economy can be improved. So, a linear actuatorshown in FIG. 12 was applied. The sleeve 8 is provided with a lever 52for movement of the sleeve 8. A member 54 for supporting a ball 53 ismounted on the lever 52, the ball being constituted so as not totransmit rotation of a screw 56 to the lever 52. The screw 56 is rotatedby power supplied to a stator 55 to effect linear motion. Due to thelinear motion of the screw 56, the lever 52 and the sleeve 8 move sothat the shift or the like is executed. The linear actuator is not movedbecause the screw 56 is engaged with the thread portion of the stator 55with respect to reaction from the sleeve 8, and energy (power) when thesleeve 8 is fixed is not necessary. A motor comprising the screw 56 andthe stator 56 is called a wobble motor.

[0038] According to the present embodiment, there is provided a powertransmission apparatus for an automobile comprising a generator drivenby an output of the engine, a battery charged by generation output ofthe generator, and a motor driven by discharge output of the battery,wherein a clutch mechanism is provided between the output shaft of theengine and an output shaft of the generator whereby an occurrence ofinertial torque of the generator can be suppressed. Thereby, it is notnecessary to correct the inertial torque caused by the engine or themotor, thus enabling a considerable reduction in fuel cost at the timeof acceleration of the vehicle.

What is claimed is:
 1. A power transmission apparatus for an automobilecomprising: an internal combustion engine; a generator driven by anoutput of said internal combustion engine; a battery charged by ageneration output of said generator; an electric motor driven by adischarge output of said battery; and a clutch mechanism providedbetween an output shaft of said internal combustion engine and an outputshaft of said generator.
 2. A power transmission apparatus for anautomobile according to claim 1 , wherein said clutch mechanism is adevice which requires, when engaged or disengaged, no energy forengagement or disengagement.
 3. A power transmission apparatus for anautomobile according to claim 1 , wherein a clutch of said clutchmechanism is a dog clutch.
 4. A power transmission apparatus for anautomobile according to claim 3 , wherein said dog clutch is driven by alinear actuator.
 5. A power transmission apparatus for an automobileaccording to claim 3 , wherein a hub of said dog clutch is provided onsaid output shaft of the generator.
 6. A power transmission apparatusfor an automobile comprising: an internal combustion engine; a generatordriven by an output of said internal combustion engine; a batterycharged by a generation output of said generator; an electric motordriven by a discharge output of said battery; a shift mechanism providedbetween an output shaft of said internal combustion engine and an outputshaft of said electric motor; and a clutch mechanism for switching theshift provided on said shift mechanism.
 7. A power transmissionapparatus for an automobile according to claim 6 , wherein said clutchmechanism is a mechanism which requires, when engaged or disengaged, noenergy for engagement or disengagement.
 8. A power transmissionapparatus for an automobile according to claim 6 , wherein a clutch forsaid clutch mechanism is a dog clutch.
 9. A power transmission apparatusfor an automobile according to claim 8 , wherein said dog clutch isdriven by a linear actuator.
 10. A power transmission apparatus for anautomobile according to claim 8 , wherein a hub of said dog clutch isprovided on said output shaft of the internal combustion engine.
 11. Apower transmission apparatus for an automobile comprising: a mechanismin which a rotational force of an internal combustion engine and arotational force of an electric motor are synthesized or selectivelyswitched to drive a drive wheel, the rotational force of said internalcombustion engine or said drive wheel is converted into electric powerby a generator, and said electric power is supplied to said electricmotor; and a mechanism for disconnecting said generator from arotational force transmission system constructed by said internalcombustion engine and said drive wheel.
 12. A power transmissionapparatus for an automobile according to claim 11 , wherein therotational force transmission system has a mechanism for switching afirst transmission system having a first transmission ratio to or from asecond transmission system having a second transmission ratio; in thecase where rotation is transmitted by said first transmission system,the rotational force transmission system is disconnected from saidgenerator; and in the case where rotation is transmitted by said secondtransmission system, the rotational force transmission system isconnected to said generator.
 13. A power transmission apparatus for anautomobile according to claim 11 , wherein the rotational forcetransmission system has a mechanism for selectively switching a firsttransmission system having a first transmission ratio, a secondtransmission system having a second transmission ratio, and a neutralstate for disconnecting the rotational force transmission system; in thecase where rotation is transmitted by said first transmission system,the rotational force transmission system is disconnected from saidgenerator; and in the case where rotation is transmitted by said secondtransmission system and in the case of said neutral state, saidgenerator is connected to the rotational force transmission system. 14.A power transmission apparatus for an automobile comprising: a mechanismin which a rotational force of an internal combustion engine and arotational force of an electric motor are synthesized or selectivelyswitched to drive a drive wheel, the rotational force of said internalcombustion engine or said drive wheel is converted into electric powerby a generator, and said electric power is supplied to said electricmotor; and a mechanism for disconnecting said electric motor from arotational force transmission system.
 15. A power transmission apparatusfor an automobile according to any one of claims 11 to 14 , whereinmeans for holding, in a fixed state, at least one of a mechanism fordisconnecting said generator, a mechanism for disconnecting saidelectric motor or a mechanism for switching said transmission systemholds said mechanism in the fixed state merely by mechanical reaction.16. A power transmission apparatus for an automobile according to claims15, wherein means for holding said mechanism in the fixed state is awobble motor.